JPS61129596A - Main steam piping tunnel chamber with horizontal type radiation monitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for attaching a main steam radiation monitor and a protective case shape for a radiation detector, and in particular, to a method for attaching a main steam radiation monitor and a protective case shape for a radiation detector. It relates to a main steam piping tunnel room that can be used and installed horizontally, and allows the design of a reactor building with the minimum necessary installation and maintenance/inspection space.

[Background of the invention]

In the main steam radiation monitor and installation method according to the conventional technology, as shown in Figure 10.11 of the plant currently being planned, 250 steel pipes are buried in the concrete IJ floor above the main steam piping tunnel room. First, an installation/removal space 34 was required on the upper floor where the monitor was installed in order to store it together with a support structure that could be firmly fixed. In the previous plant shown in Figures 13 and 14, the building design was such that a part of the 34U aisle space could be used.
The planned plant shown in Figure 1 is currently undergoing a plant design with a building structure that is different from the conventional one, and the upper part of the main steam piping tunnel room is the central control room and cable processing room, so the above 34 and the detector access space are In order to secure 51 tons, a space of 3 m width, 27 m length, and 45 m height, totaling 81 m2, is required, making the lower central operation room 52 and the cable processing room 53 narrow and complicated in shape, and the cable tray 58 inside 53 is Approximately 6,000 cables are housed in the building, and this is the main reason why the cable extension work is difficult. Also, 51 is
It is a dirty area (radiation control area) and is located in the lower central control room 5.
2. Since the cable processing room 53, central control room 55, and cable processing room 56 are clean areas (non-radiation areas), it is necessary to separate them. A shielding wall with a thickness of 1 m and a height of 4. 5m long and 30m long, with reinforced concrete walls and the amount of concrete is approximately 135m.
are using.

Therefore, in order to reduce the space and eliminate the need for concrete, consider stopping the conventional installation method of hanging from the upper floor and using the space on the same floor as the main steam pipe tunnel cliff 30. It became necessary to do so. Therefore, by using the structural members of the planned main steam pipe support 27 and installing it horizontally, it is possible to reduce the space of at least 81 m2 on the upper floor and 135 m3 of reinforced concrete. Central control block 52
It is also possible to make the partition walls 52 and 53 simpler in shape, making the work easier. In addition, in the hanging method, it is necessary to avoid installing other system components (for example, piping, HVAC ducts, conduit pipes, etc.) in the measurement range 39 (space between the hanging device 1 and the main steam pipe 26). The invention also eliminates the need to consider this limitation.

Furthermore, it was necessary to change the shape of the protective case of the detector 1 from the conventional cylindrical shape shown in FIG. 12 to the triangular prism (prismatic) shown in FIG. 1, and to improve the mounting surface.

The conventional cylindrical shape was not suitable for horizontal mounting, so the 13th to
As shown in Figure 15, due to architectural design limitations, the detector 1 of the main steam radiation monitor suspends a steel pipe from the floor of the upper floor of the main steam pipe tunnel room 30, stores it inside the pipe, and performs measurements. The conventional type requires an installation and maintenance space 34 on the upper floor, as shown in Figures 13 and 15, and there are other system components within the measurement range 39, as shown in Figures 14 and 15. could not be installed, and coordination work during the plant implementation design,
It takes a lot of time, and the best place to install the detector is the main steam pipe 26 immediately after the reactor 31 exit (for detecting abnormal radioactivity during normal operation), but it is not suitable for the containment vessel 3.
First of all, the radiation level in the atmosphere is usually high,
It is difficult to compare with the radiation level at the time of the accident. Next, during normal operation, it is only possible to enter the inside of 35, so maintenance and inspection cannot be performed. It is also hot and humid (estimated temperature at the time of the accident was 171 degrees Celsius).

Since the humidity (room) is unsuitable for installing the detector 1, a location outside the containment vessel 35 as close as possible (physically) was selected;
The current situation is that it is installed 5 to 6 meters downstream from the center (between 5 and 25).

[Purpose of the invention]

The purpose of the present invention is to expand the effective space of the reactor building by horizontally installing a main steam pipe radiation monitor in the independent steam piping tunnel room of the reactor building of a nuclear power plant.
The main steam piping is in the provision of tunnel rooms.

[Summary of the invention]

In the present invention, the protective case shape of the detector 1 is a triangular prism (prismatic prism).
This device is installed on the main steam pipe support 27 and inside the detector guide 28 to detect radiation contained in the fluid (steam) inside the main steam pipe 26. Since the detector is installed horizontally, the installation space and The main steam piping tunnel room inside the reactor building minimizes maintenance and inspection space.

[Embodiments of the invention]

Embodiments of the present invention are shown in FIGS. 1-9.

FIG. 1 shows a radiation detector (spatial gamma image dose rate meter) 1 that employs a modified (triangular prism or prismatic) protective case. This detector detects radiation (γ) contained in the fluid in the main steam pipe.
It has the function of scramming the reactor with a signal with a numerical value of about 6 to 10 times the radiation intensity during normal operation. The two electrodes face each other, and an electric field is created at a high voltage (approximately 600 volts) between them, and the other electrode collects ions generated by the ionizing action of radiation. It is connected to an electric meter installed in the central control room via an amplifier), and the intensity of radiation is measured based on changes in the amount of electricity.

Because the shape has been improved to a triangular prism (the conventional model was only cylindrical and unsuitable for horizontal installation), the fixing rod 4, which can be installed horizontally, is used to insert the spring 21 used during installation. Since it has a threaded structure, when vertical installation is effective, such as in area radiation measurement, 4 can be removed and used as a fixing bolt hole. The present shape is a triangular prism in consideration of the extraction/attachment device and in order to expand the effective area, but if there are no restrictions on installation, a rectangular prism may also be effective.

An example of a mounting/extracting device for the radiation detector 1 is shown in FIGS. 2-6.

installing the radiation detector 1 within the detector guide 28;
Its structure consists of a threaded rod 11 fixed (but rotatable) in a rectangular detector guide 28, and a female threaded rod 2.
0 is fixed using the fixing rod 4 of the detector 1 with a spring 21 and a push metal JILF22. The spring 21 is used for the purpose of firmly fixing the detector 1 and improving seismic performance, so a closed-end type (ground) spring 21 is used.The material is stainless steel (
Select a material that does not easily rust, such as stainless steel. Further, the spring 21 can also be combined with a countersunk spring.

The cables connected to the signal connector 2 and the power supply connector 3 are connected to the cable moving wire 14 installed in the cable 28 by a pulley 24a shown in FIG.

Cable combined with cable tightening screw 24b
- The structure uses the movable fitting 23 and the cable moves with it when it is installed/removed, and the structure is such that the movement of the detector 1 and the damage caused by contact with the inner surface of the detector guide 28 accompanying the movement of the detector 1 are avoided. It has a structure that can protect the cable sheath and insulation (outer jacket).

The signal connector 2 and the power connector 3 use receptacles with coupling nuts and are structured so that they do not come off easily. Failures such as poor contact will not occur. In addition, cables (for signals and power) can be laid by burying the conduit 13 during building construction and after installing 28, or if there are restrictions due to construction (strength, space, etc.), they can be laid exposed. It is also possible to do so.

The detector 1 is moved by the combination gears 16 to 18.Actually, by operating the handle 19 attached to the gear 16 and transmitting its rotational force in the order of 17 and 18, the threaded rod 11 is rotated. The detector 1 is pushed forward using a female threaded rod 20.

At that time, the power and signal cables can be moved together with 1 at 23 attached to 14.

The detector 1 is installed with a detector fall prevention plate (device) 15 for the purpose of preventing damage to the detector due to falling when pulled out during maintenance and inspection, and for improving workability. .

FIGS. 7 to 9 show the overall view (front view and top view) of the detector of the present invention installed horizontally in the main steam pipe tunnel, and show the view of the reactor containment vessel 36 of the main steam pipe 26. The main steam second isolation valve 25 is installed at the part closest to the outlet of the reactor containment vessel through hole 40, and in order to anchor the main steam isolation valve 25, a rod is connected between the main steam It is fixed to the pipe support 27.

The detector 1 includes a detector guide 2 on the 27 structural members.
8 is attached by welding, bolts, rivets, etc. and stored therein.

27 requires extremely high seismic performance (because 26, including 25, is at the reactor pressure boundary), and the strength of its structural shape has been ensured through computer analysis), - Membrane structure The rolled steel material (8841) etc. are combined into an H shape with nine welded structures, so when the detector is installed,
Design considerations regarding the seismic properties of the support and detector guide should be kept to a minimum of checking the strength of the guide mounting method. Therefore, for the guide 28,
No special support is required.

The detector guide 2B is made of stainless steel in consideration of the high temperature and humidity atmosphere during construction.

In this embodiment, the detector 1 is constructed so that maintenance, inspection, and installation can be performed from both ends of the guide.

〔Effect of the invention〕

If the main steam piping tunnel room having the horizontal radiation monitor of the present invention is adopted as an atomic couplant, a space of 81M2 including the installation/removal space 34 and the detector access space 51 shown in Fig. 10.11 will be unnecessary. Since there is no need for a shielding wall, approximately 135 m' of concrete can be saved.

Furthermore, in order to make the lower central operation room 52 and the cable processing room 53 spacious and simple (straight line structure), a cable tray 58 is used.
installation and 174 cables totaling 6,000 (approximately 150
0 wires) can improve the efficiency of wire extension work. Further, the measurement range 39 shown in FIG. 8 is reduced to about 175 compared to the conventional one, and furthermore, since components of other systems cannot be installed due to the position, adjustment work is no longer necessary. Further, by making the protective case shape of the detector 1 triangular prism (prismatic) as shown in FIG. 1, horizontal installation is possible as shown in FIG. 8.9.

In addition, as shown in FIG. 11, the detector 1 is connected to the main steam secondary
It is possible to install it on the support 27 immediately after 5 (between 35 and 250, which is the original measurement point), and it can be installed close to it.

1 In the present invention, only one detector 1 is stored in the protective case, but by storing multiple detectors,
Furthermore, the number of attachment/extraction devices can be reduced, which doubles the effect.

For example, if two detectors are housed in a protective case, the number of guides 28 and extraction devices will be reduced by half, and only two sets will be needed.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the radiation detector of the present invention, FIGS. 2 to 5 are diagrams showing combination examples of the radiation detector mounting and extraction device of the present invention, and FIG. 6 is the detector insertion device of the present invention. Detailed view of the attachment part, Figure 7 is a bird's-eye view of equipment installation according to the present invention, Figure 8 is a front view, Figure 9 is an ANA view, and Figure 10 is a plan view of the reactor building frame in the planned plant. , Fig. 11 is a side view of the vicinity of the main steam pipe radiation monitor attachment part, Fig. 12 is an explanatory diagram of the radiation detector of the conventional panel, Fig. 13 is a sectional view of the entire installation, and Fig. 1
FIG. 4 is a plan view of the attached portion, and FIG. 15 is a sectional view of the attached portion. 1-...Detector, 2...Signal connector, 3...
・Power supply connector/lid, 4...Fixing rod, 5...
・Bolt, 11... Threaded rod, 12... Cable,
13... Electrical conduit, 14... Cable moving wire, 15... Detector fall prevention plate, 16-18... Gear, 19... Nodle, 20... Female threaded rod, 21...Spring, 22...Press fitting, 23.
...Cable moving bracket, 24a...Pulley, 24b...
・Tightening screw, 25... Main steam second isolation valve, 26...
Main steam pipe, 27...Main steam pipe support, 28...
Detector guide, 30...Main steam piping tunnel room, 3
1... Nuclear reactor, 32... Main steam first isolation valve, 33.
...Steel pipe for detector installation, 34...Mounting and removal space, 35...Reactor containment vessel, 36...Reactor building,
37...Support, 38...Column, 39...Measurement range, 40...Reactor containment vessel through hole, 51...Detector access space, 52...Lower central control room, 53...・
- Cable processing room for the above, 54... Main steam third isolation valve, 55... Central control room, 56... Cable processing room for the above, 57... Shielding wall, 58... Cable tray.

Claims (1)

[Claims] 1. A main steam piping tunnel room having a horizontal radiation monitor characterized in that the protective case of the radiation detector (space gamma ray dose rate meter) has a triangular prism (prismatic) structure.